Hasselblad 500 C/M problem with a Zeiss Planar 80, mirror dos not return under specific conditions.

[Hans_500CM]

I’m new here, thank you for accepting me.
My first post has a mystic title. Because the problem is rather odd.

Hasselblad 500C/M fully serviced
Planar 80 fully serviced + the back lens exchanged (originall lens had damage)

When I make an exposure with this lens set at a position between infinitve and -about- 8 meter, the mirror does not release completely after the exposure.
I know that the connection between the lens and the body should make this happen, but for some reason this mechanism is stuck. But only between 8 and infinitive.
Of course I have  checked the same camera with two other lenses -150 and 40 mm also fully serviced- with these lenses the above problem did not occur, everything as normal.

I made a video that shows what happens.
The image shows the mechanical part that transfers function to the casing with the mirror mechanism.
I suspect that this part (on the lens) is not moving free anymore but I think it’s odd that it only happens between 8 meters and infinity set on the distance dial.

 

Before I send the lens back to the firm that did an overhaul and changed the back lens element on the Planar 80 I want to know what could be going on.

So my question here, if someone has an idea.
What could be wrong with the Planar 80, can I do something simple myself?

thank you so much for reading my post

regards
Hans (Sweden)

Edited February 2, 2023 by Hans_500CM

[rodeo_joe1]

Sounds as if the mirror is colliding with the rear of the lens at its minimum extension. That could explain the previous lens damage. 

If that's the case, you need to check the infinity focus of the lens, and that the correct replacement section has been fitted before using that lens again. Otherwise damage to lens or mirror might occur. It should be OK to fit the lens to check infinity focus, but not to fire the shutter with it fitted. 

My pure guess is that maybe the focussing helicoid has been disassembled at some point and been incorrectly set up during re-assembly. This could push the entire optical group too far back such that it collides with the mirror. - Emphasising that this is just a guess, but if so the lens needs expert adjustment, and quickly, before the rear element gets scraped by the mirror (again?). 

Edited February 2, 2023 by rodeo_joe1

[Moto-Uno]

Not too sure if my experience with the LOVELY Kowa lenses is relevant , but if I set the helicoils incorrectly 

on reassembly the Infinity marks wouldn't line up , but then I know diddly squat about hasslbad lenses 🙂 .

[rodeo_joe1]

8 hours ago, Moto-Uno said:

Not too sure if my experience with the LOVELY Kowa lenses is relevant , but if I set the helicoils incorrectly 

on reassembly the Infinity marks wouldn't line up , but then I know diddly squat about hasslbad lenses 🙂 .

Lenses vary greatly in their construction, and it also depends whether the inner or outer helicoid has been inserted at the wrong thread start. 

I just had a Minolta lens apart that had a third ring with a very fine thread for infinity adjustment. That one nearly caught me, because I hadn't touched the main helicoid. Luckily I'd scribed up the alignment before moving it.

P.S. The only thing lovely about Kowa lenses is that they're no longer made! 🤭

Edited February 3, 2023 by rodeo_joe1

[Moto-Uno]

^ I was hoping for that response 🙂 . The AMAZING Kowa lenses also have triple heli-coil and that has kept

me busy trying to mark the exact spot where each had become free . That plague for the last few years gave

me plenty of time (and patience testing) to practice the re & re with my Absolutely Thrilling selection of Kowa cameras

and lenses .

[rodeo_joe1]

On 2/4/2023 at 2:42 AM, Moto-Uno said:

^ I was hoping for that response 🙂 . The AMAZING Kowa lenses also have triple heli-coil and that has kept

me busy trying to mark the exact spot where each had become free . That plague for the last few years gave

me plenty of time (and patience testing) to practice the re & re with my Absolutely Thrilling selection of Kowa cameras

and lenses .

Honestly, when a camera system spends more time being repaired/maintained than it does taking pictures, it's time to abandon it and find something else. Something like an old metal-bodied Mamiya 645 1000s - a camera that's only suffered from the minor aggravation of a sticky self-timer in all the decades that I've owned it. 

However, the optically excellent 70mm leaf-shuttered Mamiya lens is another story, but I bet nothing like the pain of keeping a Seikosha-shuttered Kowa 6 lens fully operational.

[Hans_500CM]

On 2/2/2023 at 6:24 PM, rodeo_joe1 said:

Sounds as if the mirror is colliding with the rear of the lens at its minimum extension. That could explain the previous lens damage. 

If that's the case, you need to check the infinity focus of the lens, and that the correct replacement section has been fitted before using that lens again. Otherwise damage to lens or mirror might occur. It should be OK to fit the lens to check infinity focus, but not to fire the shutter with it fitted. 

My pure guess is that maybe the focussing helicoid has been disassembled at some point and been incorrectly set up during re-assembly. This could push the entire optical group too far back such that it collides with the mirror. - Emphasising that this is just a guess, but if so the lens needs expert adjustment, and quickly, before the rear element gets scraped by the mirror (again?). 

The lens is not on it's way back to the workshop. We'll see ....

The previous damage of the lens was -I think- not caused by the mirror.

Edited February 6, 2023 by Hans_500CM
text adjustment

[Gus Lazzari]

Hans_500CM, do you see the 'carve-out' in the tube that holds the rear group? (The lower part of the tube wall).

That exists for the mirror rise & fall clearance. Your 'shop' obviously doesn't know that this special clearance needs to be positioned properly.

One of their 'guys' just tightened the replacement rear group without knowing (and checking) that if it didn't tighten it to the correct position, it will require either a thickness shim or the application of Loctite to the threads (then set the position).

Finally, let me add, that whoever this supposed 'tech' is, they really should consider a simple step to their service, by adding some flat black paint touch-up to the marred surfaces caused by someone's careless use of tools...

[rodeo_joe1]

On 2/6/2023 at 2:20 PM, Gus Lazzari said:

... by adding some flat black paint touch-up to the marred surfaces caused by someone's careless use of tools...

You don't even need a tin of paint these days. A black permanent felt-tip marker does the job and dries near instantly. 

[andyfalsetta]

If you want to prove Rodeo Joe's theory, snip out a postage stamp sized square made out of the sticky part of "sticky notes".  Stack up five or ten of them and place the stack dead center on the lens.  Now do your shutter release test.  In theory, the shutter would remain stuck for a lot longer if the mirror is now being held by the paper sticky notes.  

It sounds like the helicoid and lens group is completely out of position.  This probably was done by a previous tech and the folks who just did your CLA just assembled it the way it was (thinking it was correct).  And as Joe said, (other than the test I suggested) don't use that lens until it has been repaired.